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Home , Baby corn, Corn nut, Flour corn, Quality Protein Maize, Sweet corn, Waxy corn

Based Products Compiled and Edited by Dr Shruti Sethi, Principal Scientist & Dr. S. K. Jha, Principal Scientist & Professor Division of Food Science and Postharvest Technology ICAR-Indian Agricultural Research Institute, Pusa New Delhi 110012

Maize is also known as Corn or Makka in Hindi. It is one of the most versatile crops having adaptability under varied agro-climatic conditions. Globally, it is known as queen of due to its highest genetic yield potential among the cereals. In India, Maize is grown throughout the year. It is predominantly a kharif crop with 85 per cent of the area under cultivation in the season. The of America (USA) is the largest producer of maize contributing about 36% of the total production. Production of maize ranks third in the country after rice and wheat. About 26 million tonnes corn was produced in 2016-17 from 9.6 Mha area. The country exported 3,70,066.11 MT of maize to the world for the worth of Rs. 1,019.29 crores/ 142.76 USD Millions in 2019-20. Major export destinations included Nepal, Bangladesh Pr, Myanmar, Pakistan Ir, Bhutan

The has highest energy density (365 kcal/100 g) among the cereals and also contains namely, B1 (thiamine), B2 (), B3 (riboflavin), B5 (pantothenic acid) and B6. Although maize kernels contain many macro and micronutrients necessary for human metabolic needs, normal corn is inherently deficient in two essential amino acids, viz and .

Maize is for human being and quality feed for animals. It has diverse uses. It can be transformed into varied products. Maize serves as a basic raw material as an ingredient to thousands of industrial products including , oil, , alcoholic beverages, food sweeteners, pharmaceutical, cosmetic, film, textile, gum, package and paper industries etc The starch obtained from maize can further be transformed into a number of valuable food and pharma ingredients. The waste or residue generated during all these processes can be further used for fuel production or used as livestock feed.

Corn classification It may be classified as , , , pop corn, , , QPM, . The quantity and quality of varies among different types of corn. Flint corn has hard and glossy endosperm with smooth and hard pericarp. Flour corn consists of endosperm made of soft starch and thin pericarp. Dent corn has partly soft endosperm and partly hard endosperm and thus falls between flint and flour corn. Dent corn has dent when it gets dried. Pop corns have small kernels with hard endosperm. Sweet corn possesses sugary which slows down the conversion of to starch in the grain. Waxy corn has starch made of 100% .

This deficiency of essential in maize has been genetically overcome by development of (QPM) which contains twice the amount of lysine and tryptophan, thus making it rich source of quality protein. It has been found that QPM yields 10% more grain than the traditional varieties of maize. Also, QPM contains 70-100% more of lysine and tryptophan than the most modern varieties of tropical maize. These two amino acids allow the body to manufacture complete , thereby eliminating wet . In addition, tryptophan can be converted in the body to niacin, which theoretically reduces the incidence of . It has also been reported that QPM have lower glycemic response as compared to milled rice and rice-corn grits making it suitable for diabetic people. Introduction of this QPM in the regular diet as diversified product can definitely help in solving the problem of malnutrition to certain extent.

Lot of research in targeted towards development of specialty maize such as quality protein maize (QPM), sweet corn, pop corn, baby corn, high oil corn etc. Some of the varieties released I India regarding these are mentioned in Table below.

Type of corn Varieties developed and released in India Quality Protein Maize Shakti-1, Shaktiman-1, Shaktiman-2 Sweet corn Maduri, Priya Sweet Corn Pop corn Amber pop corn, VL pop corn Baby corn Co1, Him123, Early composite, VL64, PEHM-1, PEHM-2 High starch Ganga111, Hi-starch, Deccan 103, Deccan 105, Trishulata, Sheetal, Paras High oil Source populations HOP-1, HOP-2 Source: Technologies for processing specialty maize in India (2003) Directorate of Maize Research, ICAR, New Delhi and Angricultural Research Station, Amberpet, ANGRAU, Hyderabad

Indian Institute of Maize Research (IIMR), Ludhiana under the aegis of Indian Council of Agricultural Research has documented the of maize developed by All India Coordinated Research Project on Maize (AICRPM) and released for cultivation in India (https://iimr.icar.gov.in/cultivars-2/) some of which are as given below:

Speciality maize Maize cultivars developed under AICRPM QPM • Pusa HM-8 Improved (AQH-8), ICAR-IARI, New Delhi • Pusa HM-9 Improved (AQH-9), ICAR-IARI, New Delhi • Pusa HM-4 Improved (AQH-4), ICAR-IARI, New Delhi • Pusa Vivek QPM-9 Improved (APQH-9), ICAR-IARI, New Delhi • Shalimar QPMH-1 (KDQH-49) SKUAST, Kashmir • Shaktiman-5 (MHQPM 09-08) Rajendra Prasad Central Agriculture University Sweet corn • Shalimar Sweet Corn-1 (KDM-1263SC) SKUAST, Kashmir • VL Sweet Corn -2 (FSCH-75)VPKAS , Almora • Central Maize VL Sweet Corn 1 (FSCH18)VPKAS, Almora, Uttarakhand Pop corn • DMRHP 1402, IIMR, Ludhiana • Shalimar Pop Corn-1 (KDPC-2) SKUAST, Kashmir • BPCH-6 Acharya N. G. Ranga Agricultural University, Hyderabad Baby corn • Vivek Hybrid 27 (Central Maize VL Baby Corn 2) VPKAS , Almora High oil lines • IC0584601, ICAR-Indian Institute of Maize Research (IIMR), Pusa Campus, New Delhi (6% oil) • IC0584602, CCS Haryana Agricultural University (CCSHAU), Regional Research Station (RRS), Uchani, Karnal, Haryana (6.31% oil) • IC0589137, ICAR-Indian Institute of Maize Research (IIMR), Pusa Campus, New Delhi (6.34% oil )

Milling of Corn In corn, two types of milling are generally used. The milling practices are known as dry and wet milling. While the main objective of dry milling is to get grits (flaking grits/brewery grits), wet milling is intended to obtain starch.

Dry milling of corn Dry milling of corn consists of unit operations like cleaning, tempering or conditioning, degerming and milling. Cleaning is usually done by dry cleaning methods. Air screen cleaner, specific gravity separator, magnetic separator are employed to clean corn prior to conditioning. Tempering or conditioning of clean grain is done by addition of moisture and allowing the grain to stand for pre-fixed time. The amount of moisture and time for tempering depends upon the intended end product quality and the method of degermination and milling to be used. If the degerming is through roller mill, grain moisture need to be raised up to 15-5 to 16.5% for 2-6 hour but major end product is grit for household consumption. Degermination through Beall or similar equipment may require the grain moisture to be raised to 20-24% with tempering time 2-6 hour; flaking and brewery grits are the major products to be obtained. If brewery grits are the requirement, decorticator and roller mills could be used which may need the grain to be moistened up to 17-18% for 2-6 hour. Roller mill used for degerming and/or milling is similar to the roller mill used for modern wheat milling. There are break passages, sizing passage and the purification passage. Germ and hull are obtained as major by-products of the dry milling of corn. Germ can be used for edible oil extraction or in breakfast . Hull can be used as animal feed.

Wet milling of Corn It consists of unit operations like steeping, germ separation, fibre separation, starch and protein separation, and starch refinement. In steeping corn is dipped into water for softening of the grain. Temperature of water and dipping time is carefully controlled during the process. The water at the end of the process gets enriched with water-soluble constituents, which is used as animal feed. Steeped corn is sent to disk mill for release of germ which is separated from the mixture using hydroclone. Milling and separation of germ is carried out in multiple pass. The slurry obtained after germ separation is passed through fine screen for separation of fibre. The fibres are retained on the screen whereas the starch- protein passes through. Protin is insoluble in water and is lower in density compared to starch, so washing followed by filtration allows the starch to pass through the filter and thus separation between protein and the starch. Starch is further refined several times through washing to ensure to get pure starch. Starch is a major ingredient for several industries. Germ obtained can be used for oil extraction or in breakfast cereal. Hull and protein obtained are used as animal feed.

Value added products from normal corn Maize can be processed into variety of value added products such as corn flour, dalia, , tortilla chips, , pop corn, puffed products etc.

Corn Flour Corn flour is a flour prepared by grinding dried whole corn kernels. It contains all components of the grain ie hull, germ, and endosperm of the corn and is thus a whole grain flour. The texture of the flour is fine and smooth. It differs from , which is coarser in terms of texture. Corn flour can be incorporated into various recipes like breads, muffins, pancakes, battered and fried foods etc. Mills of various sizes from domestic level to commercial level are available in the market for making corn flour. It is important that before grinding, thorough cleaning of the grain is done removing all unwanted materials from the grain lot.

Pusa Breakfast Cereal Breakfast cereal from maize was developed by incorporating finger and carrot into its matrix through extrusion processing. Extrusion of 72% maize, 18% finger millet and 10% carrot revealed good quality product at processing parameters of 15.5% moisture content, 120°C temperature and 400 rpm screw speed. Nutritionally, it had 9.6% protein, 1.5% , 3.4% fibre, 2 mg/100g -carotene, 3 mg/100g iron and 122 mg/100g calcium. Amino acids were higher in quality protein maize based product than normal maize based product. Two essential amino acids i.e, tryptophan and lysine were 53.7% and 45% higher respectively, in QPM based product than normal maize based product.

Corn Flakes Corn flakes are prepared from the flaking grits. The unit operations involved in the process are size reduction, cooking, cooling/drying, flaking and roasting. Pressure cooking is generally recommended to induce higher ductility properties to the grits. Inclusion of 8% sucrose in cooking medium provides better flaking characteristics to the grits. Exposing the pressure cooked grits to steam results in reduction of moisture content and increase in the degree of gelatinisation.

Corn flakes are also prepared from flour through extrusion technique. The pellets are prepared from corn flour and subsequently flaked and roasted. Pellets prepared using composite flour has better flaking property.

The grits or the pellets were subjected to compression between two rollers in a roller mill. Flaked grits were roasted to bring the moisture content of grits to 4-5% (w.b.) in a rotary roasting machine.

Cooking with steam (1-2 kg/cm2 Mixing Maize grits (4-6 mesh) pressure for 2-2.5 h)

Flaking Tempering for 6-24 h Drying

Roasting (~300°C) Roasting (~300°C) Spray of solution (vitamin, ,

flavouring agent)

Packaging Shifting Tempering (6-8 h)

Tortilla chips Corn is nixtamalized by cooking with calcium hydroxide. The digested grain is then ground to obtain . The masa is sheeted to 1mm thickness and either baked or fried as need be to get tortilla chips.

Tortilla chips

Pusa Corn Nut Ready-to-eat Pusa corn nut was developed using thermal processing. The process consists of raising the moisture content of grain up to about 35% followed by heating and mixing alternately. Heating and mixing operations are continued till the moisture content is brought below 3%. The corn nut is crunchy in texture. It has protein content of 10.06%, carotenoid content of 0.844 mg/100g, ascorbic content of 12.15 mg/100g, total phenol content of 61.45 mg/100g, antioxidant content of 5.91 μmole Trolox/g. It can be coated with spices to suit the taste of people of various age-groups. Shelf life of the product is 6 months in laminated flexible packaging at ambient condition.

Pop Corn Pop corn is manufactured by thermal treatment of whole corn kernel. Grain is first conditioned (17-18%) and the conditioned grain is exposed to high temperature for short time. The grain explodes and pop corn is obtained. It is a low-calorie food with a number of flavouring possibilities. For flavouring, is mixed seasoning/flavouring. Flavours like bacon, blue cheese, spicy or salted caramel, cheesecake are used in pop corn. Pop corn is packed with the moisture proof packaging materials. Generally, corrugated outer cartons are used for the transportation and bulk handling of the packed pop corn. This is a very popular among consumers. The popcorn market in India is increasing very fast – especially in multiplexes.

Value added products from sweet corn Sweet corn is consumed fresh or canned for future use.

Sweet corn and baby corn for fresh consumption Baby corn is also known as baby sweetcorn, young corn, or cornlets. It is small and immature stalks harvested early. It is produced as a primary crop or as a secondary crop. As a primary crop, a variety is chosen and planted to produce only baby corn. Specific varieties produce more ears per plant. As secondary crop, sweet or variety is planted. The second ear from the top of the plant is harvested for baby corn. Baby corn ears are hand-picked as soon as the corn silks emerge from the ear tips, or after a few days. Since usually corn matures quickly, harvest of baby corn must be done in time. Whole cob is eaten, both raw and cooked. Several dishes are cooked and consumed using baby corn.

Sweet corn is also known as sugar corn and pole corn. It has high sugar content. It contains which regulate conversion of sugar to starch in the grain. Harvesting of sweet corn is done at immature ( stage) and eaten in different ways such as fresh (boiled, steamed, fried, roasted etc), frozen or canned. Its storage life is poor due to conversion of sugar into starch and gradually turns tough.

Freezing of sweet corn Sweet corn if allowed to mature and dry, it becomes tough and starchy and loses its characteristics. Therefore, for longer shelf life, retaining its texture and sweetness, freezing is a quick and convenient method. Before freezing, kernels are blanched (for 3-4 min in boiling water). It helps in retention of colour, nutrients, and texture of the grain. Blanched kernels are chilled in ice water. Chilling prevents from overcooking of the kernels. After chilling, it is packed and frozen at below freezing point.

Canned sweet corn The sweet corn cobs are dehusked and blanched in boiling water for 3 min to prevent browning during processing. The kernels are separated from the cobs and filled into cans containing brine solution comprising of 3% salt and 2% sugar. After removal of air by exhausting, the cans are sealed and processed at 12 psi for 55 min. The cans are cooled immediately to avoid overcooking and stored in a clean and dry place.

Value added products from baby corn Stabilized minimally processed baby corn Baby corn are used as fresh cobs in salad or as an ingredient in various cuisines. To increase the shelf stability of these cobs, shrink wrapping is a feasible intervention. The mature cobs are cleaned and treated with either 1.5% citric acid or 0.5% ascorbic acid. After air drying the baby corn cobs are placed in polypropylene trays and shrink wrapped. These cobs are stable for a period of nine days when stored under 10°C.

Stabilized baby corn

Canned baby corn Canned baby corn is a very popular product that is exported to various countries. Dehusked baby corn cobs are cleaned and blanched in boiling water for 3-4 min. Therefater, they are filled in cans and brine solution is added into the cans. The brine comprises of 3% salt, 2% sugar and 0.5% citric acid. The cans are seamed, exhausted and processed for 35 min at 100°C. The cans are immediately cooled to room temperature and stored in a clean and dry place.

Uses of The corn obtained through wet milling process can be used in multifarious ways in food industry. Corn syrups of varying intensities of sweetness are prepared by breakdown of the starch with help of acid and enzymes. The starch may further be modified by different chemical and physical approaches to yield with varied functional properties that are product specific. Starch is used as an adhesive in paper industry or textile industry. Sorbitol and mannitol are two developed by conversion of starch that are used in products of daily use such as toothpaste, cosmetic and pharmaceuticals. Biodegradable polymers may also be developed from the extracted corn starch that are a potential alternative to the plastics used that cause environmental pollution.

Corn sweeteners Starch obtained from corn after wet milling can be hydrolyzed to glucose by the action of acid as well as enzymes. The starch slurry should be highly pure and devoid of any residual protein to obtain pure syrups (Hobbs, 2003). To remove the residual protein from the slurry, the pH of the corn starch slurry is adjusted to 4.7 to precipitate the protein that is removed as sludge. Further, filtration is carried out using a rotary vacuum filter to remove any other insoluble material to obtain the pure starch slurry. Production of sweeteners involves the following unit operations:

Corn syrups The initial step for manufacture of is to gelatinize the obtained starch under heat and pressure. The application of high temperature and pressure further helps to liquefy the starch by breakdown of glycosidic bonds. Addition of acids and enzymes further adds to the liquification process to yield a starch slurry. Enzymes maybe employed to obtain a mixture of short, medium and long chain saccharides in the slurry. Different ways to obtain the sweet syrups are as follows:

Acid hydrolysis This process involves the use of strong acids such as hydrochloric acid to reduce the pH of the slurry from 4–5 to about 1.8. The acidified slurry is subjected to high temperature (130-160°C) for about 10min under pressure of 72 psi under controlled conditions to cause liquification. The glycosidic bonds get cleaved and yield syrups of varying DE (dextrose equivalents). DE is an indicator of the reducing sugars present in the syrup. DE can be varied under influence of varying temperature, pressure and exposure time. Reaction is terminated by cooling of the slurry and neutralization of the acid. To avoid off taste development during acid conversion of starch slurries, the DE is often maintained between 25-40.

Acid/Enzyme Conversion To prevent bitter after taste developed during excessive acid hydrolysis, a combined process using both acid and enzyme has been developed. The acid breaks the glycosidic bonds to some extent. Further the hydrolyzed saccharide slurry is mixed with enzymes. Enzymes such as α-amylase, β-amylase or glucoamylase maybe used to further thin the starch slurry. Random action of α-amylase yields high molecular weight polyscaccharide, maltodextins. β-amylase on the other hand targets the glycosidic bond after every two glucose units to yield a maltose syrup. Glucoamylase breaks the branching points to yield individual glucose units. Thus, depending on the enzyme employed and the degree of depolymerization, syrups of different sweetness intensities can be produced.

Enzyme-Enzyme conversion A third method to depolymerize the corn starch includes the use of only enzymes. The starch is firstly gelatinized by subjecting it to steam. Gelatinized starch is readily available for enzyme digestion. Introduction of α-amylase at this stage yields a slurry of very low DE. Further, addition of other enzymes takes place to yield high fructose corn syrup, high maltose corn syrup, liquid dextrose and other corn sweeteners.

Purification and Decolourization After filtration, the starch slurry has a light yellow colour and also contains trace levels of many organic impurities such as amino acids, peptides, and hydroxymethylfurfural. These upon reaction with reducing sugars, contribute to the formation of undesirable flavors and color in further downstream processing steps. Powdered or granular carbon is used for decolorization. The hot syrup (70–80°C) is pumped through a bed of carbon to absorb the coloured compounds, filtered and sent for purification. Ion exchange resins are used for removing the minerals and other organic impurities.

Concentration Concentration of final syrups takes place in multiple-effect falling-film evaporators. The syrup flows down the evaporator walls under vacuum to vapourize a portion of water. The remaining liquid syrup is discharged from the bottom. Water is evaporated in a staggered manner in multiple stages, where at each stage boiling takes place at lower temperature and pressure. This is necessary to avoid unwanted discolouration of syrup.

High Fructose Corn Syrup Corn is the major source of HFCS. An acid-enzyme conversion is employed to yield HFCS. A saccharified slurry with the 95% dextrose hydrolyzate is the substrate for HFCS production. The purified and decolourized slurry is passed through columns of immobilized glucose isomerase enzyme to yield HFCS of the desired fructose content. Majorly, three variants of HFCS are in use:  HFCS-90 (90% fructose and 10% glucose)  HFCS-42 (42% fructose and 58% glucose) and  HFCS-55 (55% fructose and 45% glucose). Because of the high fructose content, HFCS is sweeter than sucrose and is thus used extensively as sweetener in various food products such as bakery toppings, juices, carbonated drinks, canned , soups, sauces, condiments, ice cream, frozen desserts, yogurt, flavored milk and many other processed foods.

Advantages of HFCS over sucrose  Higher sweetness  Better solubility  Does not crystallize  Since, it is in liquid form it has better applicability in liquid formulations  Its acidic nature imparts preservative effect that reduces the use of other preservatives. Easy transportation

Maltodextrins are nutritive saccharide polymers derived from starch that are not sweet tasting. They comprise of glucose units joined through α 1,4 linkage and have a DE<20. Maltodextrins have been given a GRAS (generally recognized as safe) status by the US Code of Federal Regulations (CFR) (21 CFR 184.1). Acid-enzyme or enzyme-enzyme processes are exploited to yield maltodextrins from the corn starch slurry. Similar to corn syrups, maltodextrins may be refined using carbon and demineralized. Further, they are spray-dried into free flowing powder for storage (Hobbs, 2003). Maltodextrins are sprayed on instant coffee, tea and dry soup mixes to prevent adhesion and keep them free flowing.

Dextrose Dextrose is another sweet saccharide that can be obtained from the corn starch slurry and is often referred to as corn sugar. It is approved as GRAS and may be as anhydrous or monohydrate type. For production of dextrose, α-amylase is added during the liquification process. To promote saccharification, amyloglucosidase enzyme is added that produces hydrolyzates of more than 95% dextrose. Similar process of filteration, carbon-refining and evaporation are undertaken to a final 71% solids concentration.

Other industrial products obtained from fermentation of corn syrups • Alcohols (ethanol, butanol, isopropanol) • Organic acids (citric, acetic, butyric, lactic) • Ketones (acetone) • Amino acids (, tryptophan, lysine) • Biopolymers (xanthun, pullulan) • Single cell protein • Enzymes

Ethanol Production Ethanol to be used as fuel can be manufactured from starch through the fermentation process as shown below.

Modification and Conversion of Corn Starch Once separated out, corn starch can be modified chemically or biologically to yield of varied functionality for different end uses. Modified starches are required to have a wider spectrum of functional attributes of the starch obtained for varied food applications. Mason (2009) has summarized the need for modified starches as follows: 1. To prolong product stability by modifying starch properties related to retrogradation i.e., increased freeze-thaw and cold storage stability, decreased syneresis and improved paste clarity. 2. To provide tolerance to processing conditions (in terms of acid, heat and shear stability) and prevent overcooking (in terms of altered peak viscosity and pasting temperature). 3. To impart desirable texture i.e. alteration in viscosity, gel forming ability and gel strength based on product.

Starch modification can be brought about by chemical or physical means.

Chemical modifications To achieve the above mentioned objectives corn starch obtained after wet milling maybe subjected to either of the below mentioned chemical modifications. 1. Stabilization 2. Conversion

Stabilized or substituted starches Such reactions involve the reaction of native corn starch with ethers or esters to impart better stability to their suspensions. The added functional groups prevent the starch molecule to reassociate and lower their tendency to retrograde. Such reactions lower the gelatinizing and pasting temperatures and increase the water holding capacity and gel strength. Propylene oxide is commonly used for such alterations in property. It attaches to the chain in an ether linkage (hydroxyl propylated starch) and imparts process stability. Similarly, in the presence of ethylene oxide, the native starch can be modified to hydroxyethylated starch.

Stabilized esterified starches are also used in the food industry. Acetic anhydride, 2-octenylsuccinic anhydride and succinic anhydride are used to develop esterified starches. Cationic starches are another class of substituted starch that are made by addition of a tertiary amine or quaternary ammonium group to the polysaccharide chain. Addition of the charged inorganic phosphate ester in the form of orthophosphates or sodium tripolyphosphate to starch moieties yields another type of substitute starch.

Converted starches Native starch may be converted by depolymerization reactions (hydrolysis, dextrinization) and oxidation using chemicals. Hydrolysis involves the reaction of the corn starch slurry with an acid below the gelatinization temperature to yield acid-thinned starch. The viscosity of the suspension decreases as the glycosidic bonds break. Oxidized starches are obtained by reaction with sodium hypochlorite. This bleaches the colour of the slurry as well as improves paste stability. These converted starches reduce the molecular weight of molecules and allows for development of higher solid pastes as more of this starch will be required to get similar viscosity as native starch. This can better the mouthfeel and body of the product into which these converted starches are added to.

Physical modifications Physical modification of corn starch maybe achieved by thermal or non-thermal methods. The starch obtained is devoid of any chemical residue and can be easily used in food products. The physical treatments alter the physical structure of starch without breaking the glycosidic bond.

Thermal methods Pregelatinization Pregelatinized starches are precooked and dried starches. They are also referred to as instant starches. Such starches show no retrogradation, are cold water soluble and hydrate readily. An increase in viscosity is however observed upon heating of their aqueous suspensions. Gelatinization of starch is achieved by subjecting the native starch on or between superheated steam drum rollers. The dried starch is scraped off and powdered. Another method to achieve gelatinization is by passing the moistened starch through an extruder under high temperature and pressure followed by drying and size reduction.

Granular cold water soluble starches These are also classified as instant starches since they are also pregelatinized. The starches swell to the extent of losing their crystalline order. Aqueous alcohol is used to treat the native starch upto the swelling temperature. Such starches hydrate and swell rapidly without disintegration under ambient conditions. These are used in confectionary and instant puddings.

Annealing Annealing is a hydrothermal treatment wherein starch is hydrated to a moisture content of over 40% and held at below gelatinization temperatures (50°C) for prolonged periods. The modified starch thus developed has a better stability and improved gel strength.

Non-thermal treatments Milling, ultrasonication, pulse electric field and high hydrostatic pressure are a few non-thermal techniques that modify the corn starch. Degree of milling determines the extent of damaged starch produced. This further influences the solubility, water absorption capacity and the digestion by enzymes. Presence of high damaged starch increases the water absorption capacity of starch. Moreover, the opened starch structure is prone to amylase attack. Processing conditions with ultrasound (power, temperature etc.) influence the depolymerization of starch constituents resulting in functionality changes of starch. Water absorption and swelling increase while the breakdown of structure results a lowering of the peak viscosity of the starch suspension. Similar influence is seen when subjected to pulse electric field. Alteration in gelatinization temperature of native starch can be achieved by forcing water inside the granule under pressure as is the case in high hydrostatic pressure technology. Such alterations in functional properties of starch can govern their end-use applicability.

Utilization of corn processing waste Corn cobs generated as a waste from the corn processing industry is a very rich source of such as pentosans. The pentosan is hydrolyzed to the monosaccharide pentose that is further converted to furfural, an important chemical with variety of applications including plastics, pharmaceuticals, agrochemical and conversion to bio-fuel (Agirrezabal-Telleria et al., 2014). It can be used as a substrate for production of fuel alcohol by using the yeast, Pichia stipitis in conjunction with an enzyme. The process developed can produce nearly 200 g of ethanol per kg of dry matter (Hang and Woodams, 2001). Citric acid production can also be achieved through fermentation of corn cobs using Aspergillus niger NRRL 2001. Maximum output of 400 g of citric acid per kg of dry matter of corn cobs can be achieved under favorable fermentation conditions (Hang and Woodams, 2001). Similarly, production of lactic acid can also be achieved through fermentation of corn cobs by Rhizopus oryzae (Ruengruglikit and Hang, 2003).

Corn Oil Oil from corn germ can be extracted either by cold expelling, or solvent extraction or a combination of expelling and solvent extraction. Since the oil content in maize kernel is very less and therefore cold pressing does not offer god extraction yield. However, for pre-pressing it can be used. Remaining oil can be extracted using solvent extraction. Solvent extraction method is most efficient method of extraction. Though the solvent (n-hexane) used in the extraction has toxic effect, there is search for alternate method for oil extraction. Various other techniques like super critical fluid extraction, enzyme assisted extraction are being explored. The germ residue left after solvent extraction can be used as animal feed. The extracted oil is a crude oil as it contains various impurities. It contains 95% triglycerides besides containing minor compounds like free fatty acids, waxes, phospholipids, pigments, and odourous compounds. To make it edible oil, the impurities are to be removed through various operations like refining, bleaching, deodorization etc.

Quality Control Pre-requisite programmes (PRPs) PRPs such as good agricultural practices (GAP), good manufacturing practices (GMP) and good hygienic practices (GHP) must be working effectively within the process before HACCP is applied. If these PRPs are not functioning effectively then the introduction of HACCP will be cumbersome. Good Agricultural Practices  Agricultural practices should be managed to ensure that food is safe and wholesome for the consumer.  Land used for crop production should not be contaminated with industrial chemicals, heavy metals or environmental waste.  Control of pests, diseases by different means should not be compromised with food safety. Such hazards tend to enter the food chain rendering the commodity unfit for human consumption.  Good Storage Practices (GSP) should be followed for storage of maize crop throughout the supply chain.

Good Manufacturing Practices  Processing plant premises should be designed to minimise contamination.  Process plant design and layout should permit proper maintenance, cleaning and disinfection to minimise contamination and prevent access to pests.  All surfaces coming in contact with food should be from non toxic material and should be easy to maintain.  Effective measures for temperature and humidity control, equipment maintenance, potable water supply, packaging, waste management should be in place to control food hazards.

Good Hygienic Practices  Food handlers should be trained for maintaining hygiene and sanitation so that they do not contaminate food.  Personal cleanliness should be followed strictly so as to make Food Safety Management System successful. Hazard Analysis Critical Control Point (HACCP) HACCP is a systematic approach to the identification and control of hazards which are significant for food safety. This system was developed by The Pillsbury Company in the early 70's to ensure the safety of foods for the United States space program. HACCP is built on well established quality management pre requisite programms of Good Agricultural Practice (GAP), Good Manufacturing Practice (GMP) and Good Hygienic Practice (GHP). HACCP system constitutes of the following basic steps: i) assemble a multidisciplinary HACCP team ii) describe product and identify intended use iii) construct flow diagram; on-site confirmation iv) identify hazards, their severity and their risks, v) determine critical control points (CCP's), vi) establish critical limits, vii) monitor CCP's viii) establish corrective action for CCP deviation, ix) verify the procedure, and x) document and keep record

Raw maize is contaminated with dust, soil and airborne microorganisms. Some of these get removed during steeping process. Raw maize should be procured having mycotoxin levels below the maximum residue limits, critical limit for aflatoxin B1being 50 µg/kg. Thus, HACCP plan should be implemented at every stage. If the in-process water is contaminated, the entire plant will be infected. Steep liquor water is highly susceptible to microbial attack and thus needs most attention. The cloth inside the centrifuge is loaded with wet starch that can support the growth of microorganisms, especially at ambient temperatures. Drying process significantly influences the microbial count in starch. Effective sanitation procedures should be followed to reduce the microbial load to a minimum. Post process contamination should also be avoided by use of proper packaging and recommended storage temperature. Personnel should be trained and made aware of potential hazards and know the criteria for control, monitor and take corrective action.

References 1. Agirrezabal -Telleria, I., Requies, J., Güemez, M. B., and Arias, P. L. (2014). Dehydration of d- xylose to furfural using selective and hydrothermally stable arenesulfonic SBA-15 catalysts. Appl. Catal. B-Environ. 145, 34-42. 2. Hang, Y.D. and Woodams, E. E. 2000. Corn :a potential substrate for production of citric acid by Aspergillus niger. Food Sci. Technol. 33:520-521. 3. Hang, Y.D. and Woodams, E.E. 2001. Enzymatic enhancement of citric acid production by Aspergillus niger from corn cobs. Food Sci.Technol.34:484-486. 4. Helstad, S. 2019. Corn Sweeteners. Chapter 20 In: Corn: Chemistry and Technology (3rd edition). Elsevier Inc. 5. Hobbs, L., 2003. Corn sweeteners. In: White, P., Johnson, L.A. (Eds.), Corn: Chemistry and Technology, second ed. American Association of Cereal Chemists, St. Paul, MN, pp. 635–669. 6. http://agriexchange.apeda.gov.in/product_profile/prodintro/Maize.aspx 7. Mason, W.R. 2009. Starch use in foods. In: BeMiller, J., Whistler, R. (Eds.), Starch: Chemistry and Technology, third ed. Academic Press, New York (Chapter 20). p 551-591. 8. Ruengruglikit, C., and Hang, Y. D. 2003. L(+)-Lactic acid production from corn cobs by Rhizopus oryzae NRRL 395. Food Sci. Technol. 36: 573-575.